The Sample Study on Avifaunal Diversity of North Sikkim was conducted by Lina Chatterjee in the month of October 2018 and the identification and data analysis was done by Nature Mates-Nature Club team. This dataset covers the areas Lachen, Yamthung valley, Lachung, Gurudongmar. The study area covers varied habitats like Alpine pasture, hilly area, waterfalls, meandering rivers, rhododendron forest, River, hot spring, grazing pasture, rolling meadows with pine and silver fir lining sides, Cold alpine lake, snow capped mountain. All the birds are identified up to the species level. A total of 108 species of birds we recorded belonging to 36 families, 9 orders This dataset also includes the life stage, activity and behaviour of the birds observed. There are few species of birds which are widespread in Gurudongmar but are uncommon elsewhere, of which Rufous-necked snowfinch (Pyrgilauda ruficollis), Horned lark (Eremophila alpestris) were recorded during our study.